How should we decide what is morally right and what is morally wrong? For much of human history, the teachings of religion were presumed to be a large part of the answer. Over time, two developments challenged this. The first was the establishment of the discipline of moral philosophy. Foundational texts, such as Kant’s Groundwork of the Metaphysics of Morals, and the growth of coherent, non-religious approaches to ethics, notably utilitarianism, served to marginalise the role of religion. And then the twentieth century saw the rapid growth of evolutionary biology with an enthusiastic presumption that biology was the source of ethics. What space do such developments leave for religion in ethics? One can be most confident about the validity and worth of an ethical conclusion if three